Computation chart



Get. 28, 1952 A. l. SORRELS 2,615,631

COMPUTATION CHART Filed July a, 1947 Patented Oct. 28, 1952 UNITEDSTATES PATENT OFFICE COMPUTATION CHART Aaron I. Sorrels, Chicago, Ill.

Application July 3, 1947, Serial No..758,764

3 Claims. l

arrangement of parts hereinafter described and claimed, and will be morereadily and easily understood by reference to the'accompanying drawingsforming apart of this application, and in which:

Fig. 1 is afront face view of my computation chart embodying theinvention, assembled in operative position for use, showing calendarScale A and menstrual Scale B; and

,Fig. 2 is a cross section taken on diametrical line 2-2 of Fig. 1;

The embodiment of the invention illustrated inthe drawingscomprises arigid supporting bottom member 3! having a protruding tab 35, a basemember injthe form of a disc 2d, preferably constructed of cardboard orother similar material and wherein each part is provided with acentrally located hole 2% adapted to receive a rivet 22 having a burr23, or other device'for pivotally attaching other elements thereto. Thefront face of the disc 26 carries a Scale A, reading clockwise,comprising circumferentially positioned and radially arranged graduationmarks 24 forming spaces 25, divided into four tables,

CO-Willi table fa showing February, 28 spaces for estimating 28 days;table 1, March, August and December, 31 spaces for estimating .31 days;table 8, April, June, September and November,

30 spaces for estimating 30 days; and table 8 showing January, May, Julyand. October, 31 :spacesfor estimating 31 days.

The above combinations of months discloses the purpose of placwhich themenstrual period begins and continuing over into the next table, it ispossible to arrive at a correct date calculation without difliculty, aswill be readily understood.

It is common authoritative knowledge that normal menstrual periods varyfrom approximately twenty-four to thirty days in individuals. Because ofthis variation in length a Scale B is provided which refers particularlyto menstrual periods of varied lengths. The Scale B is carried on theouter face of an arcuate indicator 25 rotatably arranged over the saiddisc 28, being pivotally mounted thereon and thereto on the rivet 22,and extends in radial alignment with the graduation marks 24 of Scale Acarried by the disc 28. The indicator 25 carries a plurality ofconcentric rows 23 of graduated spaces 25. The first or upper rownumbers 2 to 31 inclusive, corresponding to the greatest number of daysin a month. In the last radial column 29 are figures representingolifierent lengths of normal menstrual periods beginning with 24 andending with 30, showing the total number of the days in that period. Itis further to be noted that the numbering of spaces 25 in thecircumferential rows 28 indicated by the totals 24 to 30 are numbered'inreverse from 20 to 1, followed by the capital letter M. The letter M onScale B indicates the beginning day of the next menstruation period. Bythis arrangement it can be determined the exactnurnber of days from agiven 'date to the beginning or" the next menstrual period. Theencircled 15 on Scale B indicates the approximate date in theory thatconception takes place,-or at about the 15th day before the nextmenstrual flow. The numbers at the outer circumierence of Scale B alsoindicate the number of days from the start of the last period to thebeginning of the next period. An arrow 21 serves to locate the point ofsetting of the said Scale B relative to the Scale A. For personsfollowing the herein-described method of determining date of the time ofconception, which is believed to take place on or about the fifteenthday before the due date of the next menstrual period. Reference beingfurther had to lines 23 and the arrow 21.

It is generally accepted belief that the conception date occurs on thefifteenth day before the next normal menstrual occurrence. To facilitatethe ready location of this date, each or" the con centric lines carrythe letter M at its righthand termination, and an index figure as to thenumber of days in its respective concentric line of the table B bearingreference numeral 28 It Will be noted that in each concentric column theintervening spaces between 28 and II are bordered by heavy marginallines 34 and separated by a round open space, each containing the figure15. Each of these 25 spaces is believed to be the day when conceptiontakes place. This marking and margining the spaces 34 is to guide theoperator in the concentric column of a selected length of the selectedterm of menstrual period.

In use, the Scale A affords a simple arrangement of months having 28, 30or 31 days into four tables, 6, I, 8 and 9, shown in Fig. 1, by whichmenstrual periods involving a 31-day month followed by a 28-day month,as table 9 followed by table 6; a 28-day month followed by a 31-daymonth, as table 6 and table 1; a 31-day month followed by a 30-daymonth, as tables 1 and 8; and a 30-day month followed by a 31-day month,as tables 8 and 9. By this arrangement one hundred and twenty spaces 25suffice to show the twomonth period combinations in a year of 365 days.The Scale B carried by the arcuate indicator 26 shows detail mattersconcerning the menstrual period which is applicable whether the periodis wholly within one month or involves days within two consecutivemonths. Each important day in the period can easily be determined byproper arrangement of the Scale B over the Scale A. Another practicaluse of Scale B is to determine the approximate date of conception and isobtained from the use of Scale B properly set over Scale A and with thenumber of days in te menstrual period known, and then counting back 15days from the due date of the first menstrual omission, the approximatedate of conception can be learned. From this date the period ofgestation will last about 280 days.

Instructions for the use of the chart (For an example, the subjects lastperiod began February 15th. Her normal period is 28 days, making hernext period due on March 15th. Her periods vary from 26 to 30 days.)

1. To use the chart to calculate a normal period:

Step 1.Set arrow on left side of Scale B at the date last period began.In the subjects case it is February 15th, which appears on Scale A.

Step 2.--The subjects next period occurs March 15th. Keep the arrow onFebruary 15th, follow along on Scale A to the 15th. Reading below andone square to the left on the top of Scale B, We find it was a 28-dayperiod.

St p 3.Follow the above instructions on determining each period foreight to ten months.

Total 280 days days days days days days days days days days days dividedby 10, which is the number of periods, equals 28 days, which is thesubjects normal period.

2. To use the chart to determine when the next period will occur:

the date last period began. In the subject's case it is February 15th,which appears on Scale A.

Step 2.'Ihe subjects normal period is 28 days. Keep the arrow onFebruary 15th. Follow along the top of Scale B for 28 days. Read aboveand one square to the right on Scale AMarch 15th for the date nextperiod begins.

Or: Keep arrow on February 15th. Select the normal period column onScale 13. In the subjects case it is 28. Follow to the left to theletter M. Read above on Scale A-March l5ththe date next period begins.

3. To use the chart to determine the date of conception and expecteddate of birth:

Step 1.Set arrow on left side of Scale B at the date last period began.In the subjects case it is February 15th, which appears on Scale A.

Step 2.Keep the arrow on February 15th. Select the column on the rightside of Scale B, which corresponds to the subjects normal period,

' 28. Move to the left in the 28 column'to the encircled 15. Readdirectly above on Scale A- February 28ththe approximate date ofconception.

4. To determine non-fertile days of the subject:

Step 1.Set arrow on left side of Scale B at the date last period began.In the subjects case it is February 15th, which appears on Scale A.

Step 2.-To allow for the subjects occasional variation from a 26 to a30-day period, check column 28 and 30 on the right side of Scale B.

Keep the arrow on February 15th. Select column 26 on right side of ScaleB. Follow to the left to the darkly outlined number 19 and read above onScale A-February 22ndsubjects first fertile day. Then, on column 30,move to the left to the darkly outlined number 12 and read above onScale AMarch 5th--subjects last fertile day. Therefore, February 22nd toMarch 5th inclusive are the subjects fertile days.

5. Adjustments to be made on the chart for use during leap year:

1. For leap year, when the period occurs in February and extends intoMarch, one day should be subtracted from the date next normal periodbegins to allow for the 29th day of February.

2. For leap year when the period of pregnancy continues throughFebruary, subtract one day from the expected date of birth to allow forthe 29th day of February.

While I have illustrated and described a precise arrangement forcarrying the invention into a practical, effective use, this is capableof many variations, modifications and alterations without departing fromthe spirit of the invention. I therefore do not wish to be limited bythe description and drawings forming a part of this specification, butdesire to avail myself of such changes as may fall within the spirit andscope of the appended claims.

I claim:

1. In combination, a computation chart comprising a flat circular basehaving a plurality of graduations, in continual alignment adjacent themarginal edge thereof; a plurality of calendar date reading from left toright and comprising a plurality of months arranged in a plurality ofgroups having a similar ending as to the number of days therein, andanother group of months directly following having a group of months eachhaving a similar number of days but at variance with the said firstnamed group; an arcuate indicator rotatably mounted at the center ofsaid circular base; graduations at the marginal edge of said rotatableStep 1.--Set arrow on left side of Scale B at indicator arranged t bpassed t radial alignment with the graduations carried by said circularbase and reading from left to right and corresponding with calendarmonthly dates from 28 days to 31 days; a menstruational table comprisinga plurality of concentric rows comprising seven (7) rows, each of anormal duration numbering from (24) twenty-four days to (30) thirty daysarranged to read from right to left from the normal due date theparticular length of the period selected; each of the foregoing periodshaving its twelfth to nineteenth margined in heavy separation lines; andthe fifteenth day previous to the normal menstrual period arrangedwithin a circular margin indicating the date of conception.

2. A computation chart of the class described comprising a circular dialhaving a plurality of graduations reading from left to right adjacentits peripheral edge indicating days; the said graduations being arrangedsubstantially in four contiguous major groups sequentially as to thecalendar dates of the last day of a month with the first day of the nextfollowing month; an arcuate indicator rotatably mounted at the center ofsaid dial; indicia on said arcuate indicator for manually selectiveradial alignment with indicia carried by the peripheral edge of saiddial; a table of normal menstrual periods of different lengthssequentially arranged in concentric alignment adjacent the outer edge ofsaid arcuate indicator; and an interval of eight days, from the 12ththrough the 19th day before the normal due date of the next menstrualdue date, said interval in each of the periods bordered by heavy linesindicating the general period of conception.

3. The construction specified in claim 2 in which the day of conceptionis indicated by a circular space bounded by a square lined enclosure andcontaining the numeral 15.

AARON I. SORRELS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 784,660 Chritton Mar. 14, 19051,435,512 Boggio Nov. 14, 1922 2,076,242 Marquis Apr. 6, 1937 2,098,622Gronwold Nov. 9, 1937

